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1.
E. Träbert 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,26(2):147-149
The analysis and interpretation of the data presented by S. Ahmad [Eur. Phys. J. D 22, 189 (2003)] are shown to be inconsistent, and are in conflict with established atomic physics.Received: 11 July 2003, Published online: 30 September 2003PACS:
32.70.Fw Absolute and relative intensities - 34.50.Dy Interactions of atoms and molecules with surfaces; photon and electron emission; neutralization of ions - 34.80.Dp Atomic excitation and ionization by electron impact 相似文献
2.
Absolute cross sections for single and double electron-impact detachment of the S- ion have been investigated over collision energy ranges of 0-60 eV and 0-30 eV, respectively. The experiment was performed at the ion storage ring, CRYRING. The threshold energies were measured to be 6.6 eV for single detachment and 19.8 eV in the case of double detachment. The single detachment cross section has a maximum of 6.7 x 10-16 cm2 at 30 eV. The double detachment cross section was studied only in the threshold region. No sharp structures were observed in either of the cross sections.Received: 24 April 2003, Published online: 29 July 2003PACS:
34.80.Dp Atomic excitation and ionization by electron impact - 34.80.Kw Electron-ion scattering; excitation and ionization 相似文献
3.
We present a technique for describing solutions of the helium atom by using the non-orthogonal Laguerre-L2 basis functions. The frozen-core approximation is used to calculate the helium energies. The completeness of helium wavefunctions obtained is studied in terms of weights of the Gaussian quadrature. The convergence of the energies is shown as the L2 basis size increases and the completeness of the L2 wave functions is also shown for different basis size.Received: 20 August 2003, Published online: 6 January 2004PACS:
34.80.Bm Elastic scattering of electrons by atoms and molecules - 34.80.Dp Atomic excitation and ionization by electron impact 相似文献
4.
Certain important and pertinent questions have been raised by E. Träbert in his comment on the paper [Eur. Phys. J. D 22, 189 (2003)] by one of us. We provide explanations as well as new and recent data using a calibrated monochromator on the existence of the main intercombination multiplet 233 nm which is the bone of contention. It is shown that there is no conflict with the established atomic physics in the regenerative sooting discharges; only the interpretations are at variance with those of the comment.Received: 30 July 2003, Published online: 30 September 2003PACS:
32.70.Fw Absolute and relative intensities - 34.50.Dy Interactions of atoms and molecules with surfaces; photon and electron emission; neutralization of ions - 34.80.Dp Atomic excitation and ionization by electron impact 相似文献
5.
Cross sections are provided for most important collision processes of the Silicon‐Hydrides from the “Silanefamily”: SiHy (y = 1 ? 4) molecules and their ions SiH+y, with (plasma) electrons and protons. The processes include: electron impact ionization and dissociation of SiHy, dissociative excitation, ionization and recombination of SiH+y ions with electrons, and charge ‐ and atom ‐ exchange in proton collisions with SiHy. All important channels of dissociative processes are considered. Information is also provided on the energetics (reactants/products energy loss / gain) of each individual reaction channel. Total and partial cross sections are presented in compact analytic forms. The critical assessment of data, derivation of new data and presentation of results follow closely the concepts of the recently published related databases for Carbon‐Hydrides, namely for the Methane family [1, 2], and for the Ethane‐ and the Propane families [3], respectively. (© 2003 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
6.
The distorted wave Born approximation (DWBA) with the spin averaged static exchange potential has been used to calculate the triple differential cross-sections (TDCSs) for Ne (2s
2) ionization by electron impact in coplanar to perpendicular plane symmetric geometry at 110.5 eV incident electron energy. The present theoretical results at gun angles
(coplanar symmetric geometry) and
(perpendicular plane geometry) are in satisfactory agreement with the available experimental data. A deep interference minimum appears in the TDCS in the coplanar symmetric geometry and a strong peak at scattering angle
caused by the single collision mechanism has been observed in the perpendicular plane geometry. The TDCSs at the gun angles
, and
are predicted.Received: 16 July 2002, Published online: 22 July 2003PACS:
34.80.Gs Molecular excitation and ionization by electron impact - 34.80.Dp Atomic excitation and ionization by electron impact 相似文献
7.
8.
《Physics letters. A》1987,123(7):345-348
First observations of a giant resonance are reported in the cross section for I+ formation by dissociative ionization of I2 molecules by monoenergetic electron impact. 相似文献
9.
Lengthening the Lifetime of Long Plasma Channel in Air Generated by Femtosecond Laser Pulse 下载免费PDF全文
We theoretically investigate the lifetime of self-guided plasma channel in air by launching an auxiliary delayed long-pulsed laser beam following an ultrashort laser. A detailed model makes the electron-ion recombination, the attachment of electrons on neutral particles, and particularly the impact ionization and electron-detachment mechanism incorporate. The calculated results show that the temporal evolution of electron density is greatly flattened and broadened. When the auxiliary laser intensity exceeds the threshold 3.32 × 10^4 Wcm^-2, the channel lifetime is distinctly prolonged from nanosecond to microsecond, or even longer due to the electrical field enhancement. Furthermore, with the laser intensity up to 109 Wcm^-2, the impact ionization overwhelms the detachment in effect. Thus, it is an effective way to extend the channel lifetime and provides a real opportunity for applications. 相似文献
10.
Two theories, explaining the time dependence of the negative corona discharge current in air, are confronted with new experimental results. The influence of the ozone concentration on the discharge current was experimentally confirmed in dry air and in mixtures of nitrogen with oxygen. Assuming that only the dissociative electron attachment to ozone molecule is a process being responsible for a reduction of the electron component in the total mean discharge current, the mean value of the electron attachment rate constant k = (3 - 5.5) × 10?9 cm?3 s?1 was derived from the measured dependence of the discharge current on the ozone concentration. The calculated value of the rate constant k corresponds to the dissociative attachment of electron to ozone molecule via process e + O3 → products (O? or O?2 negative ions). 相似文献
11.
We have carried out distorted wave calculations for electron impact 5
2P, 6 2S and 4 2D excitations of rubidium atom at incident electron energies in the range of 10-200 eV. Results are presented for differential and total cross-sections of these excitations, Stokes parameters of the excitation of the fine-structure resolved and unresolved 5 2P and 4 2D states, complete experiment parameters for the excitation of 5 2P state and the STU spin parameters of its fine structure states. Good agreement is found on comparison of our results with the available experimental data and the earlier theoretical calculations. Except for the resonance 5
2P transition no earlier calculations were reported for the excitation of the higher 6 2S and 4 2D states.Received: 25 February 2004, Published online: 22 June 2004PACS:
34.80.Dp Atomic excitation and ionization by electron impact - 34.80.Nz Spin dependence of cross-sections; polarized electron beam experiments 相似文献
12.
Presently available laser sources can yield powers for which the ponderomotive energy of an electrons
can be equal to or even larger than the rest energy mc
2 of an electron. Therefore it has become of interest to consider fundamental radiation-induced or assisted processes in such powerful laser fields. In the present work we consider laser-induced Compton scattering and laser-assisted electron atom scattering in such fields, assuming that the laser beam has arbitrary elliptic polarization. We investigate in detail the angular and polarisation dependence of the differential cross-sections of the two laser-induced or laser-assisted nonlinear processes as a function of the order N of absorbed or emitted laser photons
. The present work is a generalization of our previous analysis of Compton scattering and electron-atom scattering in a linearly polarized laser field [Phys. Rev. A 65, 022712 and 033408 (2002)].Received: 3 November 2002, Published online: 29 April 2003PACS:
34.50.Rk Laser-modified scattering and reactions - 34.80.Qb Laser-modified scattering - 32.80.Wr Other multiphoton processes 相似文献
13.
We studied the far-infrared emission spectrum resulting from recombination of an electron with an ionized impurity of As and
Sb in germanium under impact ionization at liquid, helium temperatures. The emission peaks at the position corresponding to
the transition from the 2p
± excited state to the ground state. This observation indicates that recombination occurs through the capture by the excited
states of the donor impurity, which is consistent with the cascade trap model. The intensity of emission radiation is of the
order of 10−7 watts for the excitation power of about one watt, which implies a dominant process of recombination to be accompanied by
phonon emission. 相似文献
14.
The effect of free–bound and bound–bound resonance nonadiabatic transitions of an electron on electron–ion recombination rates in the plasma of a Ne/Xe and Ar/Xe inert gas mixture has been studied. A kinetic model of recombination has been proposed including energy relaxation in collisions with electrons, resonant electron capture to Rydberg states through three-body collisions of Xe+ ions with Ne or Ar atoms and dissociative recombination of NeXe+ or ArXe+ ions, and n → n' resonance transitions. It has been shown that effective resonance processes occurring in quasimolecular systems sharply increase both the recombination coefficient and the effect of collisions with neutral particles even at quite high degrees of ionization of the plasma. 相似文献
15.
In this paper we report on inner ionization of Xen clusters (n = 55-
2171) in ultraintense Gaussian laser fields (peak intensity I = 1015- 1020 Wcm-2, pulse width τ= 25 fs, frequency 0.35 fs-1). The cluster inner ionization process is induced by the barrier
suppression ionization (BSI) mechanism and by electron impact ionization
(EII), which occurs sequentially with the BSI. We address electron impact
ionization of clusters, which pertains to inelastic reactive processes of
the high-energy (100 eV–1 keV per electron) nanoplasma. We utilized
experimental data for the energy dependence of the electron impact
ionization cross-sections of Xej+ (j = 1-10) ions, which were fit by
an empirical three-parameter Lotz-type equation, to explore EII in clusters
by molecular dynamics simulations. Information was obtained on the yields
and time-resolved dynamics of the EII levels (i.e., number nimp of
electrons per cluster atom) in the Xen clusters and their dependence on
the laser intensity and cluster size. The relative long-time (t = 90 fs)
yields for EII, nimp/nii (where nii is the total inner
ionization yield) are rather low and increase with decreasing the laser
intensity. In the intensity range I = 1015-1016 Wcm-2,
nimp/nii = 0.21 for n = 2171 and nimp/nii = 0.09-0.14
for n = 459, while for I = 1018-1020 Wcm-2,
nimp/nii = 0.01-0.05. The difference Δnimp between
the EII yield at long time and at the termination of the laser pulse
reflects on ionization dynamics by the nanoplasma when the laser pulse is
switched off. For Xe2171 in the lower intensity domain, Δ
nimp = 0.9 at I = 1015 Wcm-2 and Δnimp = 0.4 at
1016 Wcm-2, reflecting on EII by the persistent nanoplasma under
“laser free” conditions, while in the higher intensity domain of I =
1017 - 1018 Wcm-2, Δnimp is negligibly small
due to the depletion of the transient nanoplasma. 相似文献
16.
R. Slater 《Applied physics. B, Lasers and optics》1987,42(1):17-20
The rate of build-up of N2 was measured in electron-beam-irradiated Ne/Xe/NF3 mixtures using mass spectroscopy. the amount of N2 produced indicated that N2 is the primary nitrogen bearing stable species created in these mixtures. The rate constant for dissociative electron attachment to the NF2 fragments produced in electron attachment to NF3 is estimated to be 5×10–8 cm3/s in order to explain the amount of N2 produced.This work was supported by DARPA under Contract No. DAA01-82-C-A125 and monitored by MICOM 相似文献
17.
V. Sharma B. Bapat 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2006,37(2):223-229
A spectrometer for recoil ion momentum measurements has been built for studying electron impact ionisation and dissociation
of molecules. The apparatus is described in detail, highlighting its capabilities, as well as differences in design from the
ones already in use elsewhere. Momentum spectra of ions resulting from 1300 eV electron impact on CO2 are presented. We observe a broad momentum distribution for the dissociative ionisation reaction leading to the formation
of C+, and two momentum groups in the CO+ and O+ channel. By recording multiple ions arising from the same dissociative ionisation event, we also demonstrate the formation
of fragment pairs O+:CO+, C+:O+, and O+:O+. 相似文献
18.
Effects of the nuclear charge distribution upon the total cross-section of dielectronic recombination are investigated. We calculated isotope shifts of resonance energies for H-, He- and Li-like heavy ions in the relativistic domain from Z = 54 to Z = 94. We point out that the position of the resonances is most influenced in KLL transitions in very heavy elements and their shifts are most likely to be measurable for systems with intra-shell transitions. For these systems, dielectronic recombination experiments provide a new method to determine the parameters of the nuclear charge distribution.Received: 26 July 2004, Published online: 5 October 2004PACS:
34.80.Lx Electron-ion recombination and electron attachment - 31.30.Jv Relativistic and quantum electrodynamic effects in atoms and moleculesR. chiopu: Now at Institut für Physik, Johannes-Gutenberg-Universität, Mainz, Germany. 相似文献
19.
We study two-photon double ionization of helium in its ground state at sufficiently low laser intensities so that three and more photon absorptions are negligible. In the regime where sequential ionization dominates, the two-photon double ionization one-electron energy spectrum exhibits a well defined double peak structure directly related to the electron-electron correlation in the ground state. We demonstrate that when helium is exposed to subfemtosecond or attosecond pulses, both peaks move and their displacement is a signature of the time needed by the He+ orbital to relax after the ejection of the first electron. This result rests on the numerical solution of the corresponding non-relativistic time-dependent Schrödinger equation.Received: 17 January 2003, Published online: 18 March 2003PACS:
32.80.Rm Multiphoton ionization and excitation to highly excited states (e.g., Rydberg states) - 32.80.Dz Autoionization 相似文献
20.
H. Cherkani-Hassani D. S. Belic J. J. Jureta J. Lecointre P. Defrance 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,58(1):85-94
Absolute cross-sections for electron-impact dissociative ionization of C2
H2+ and C2 D2+ to CH+, C+, C2+ , H+, CH2+
and C2D+ fragments are determined for electron energies ranging
from the corresponding threshold to 2.5 keV. Results obtained in a crossed
beams experiment are analyzed to estimate the contribution of dissociative
ionization to each fragment formation. The dissociative ionization cross
sections are seen to decrease for more than an order of magnitude, from
CH+ (5.37±0.10) × 10-17 cm2 over C+ (4.19±
0.16) × 10-17 cm2, C2D+ (3.94±0.38) ×
10-17 cm2, C2+ (3.82±0.15) × 10-17 cm2
and H+ (3.37±0.21) × 10-17 cm2 to CH2+
(2.66±0.14) × 10-18 cm2. Kinetic energy release
distributions of fragment ions are also determined from the analysis of the
product velocity distribution. Cross section values, threshold energies and
kinetic energies are compared with the data available from the literature.
Conforming to the scheme used in the study of the dissociative excitation of
C2H2+
( C2 D2+ )\left( {\rm C}_2 {\rm D}_2^+ \right), the cross-sections are presented in
a format suitable for their implementation in plasma simulation codes. 相似文献